There are many types of motors, such as outer-rotor motors. Wherein the rotor of the outer-rotor motor usually includes a yoke, a permanent magnet mounted to the yoke, an end cap connected to the yoke, and a rotary shaft connected to the end cap. However, the end caps of the rotors are mostly made of aluminum alloy, which leads to high cost and large weight of the rotor. In addition, fixing the permanent magnet relative to the yoke requires the use of glues. However, it can be hard to control the amount of the glues used. Furthermore, the yoke is formed by stacking a plurality of laminations, and the laminations need to be fixed by fixing pins passing through holes defined through the respective laminations. As a result, the fabrication of the yoke can be troublesome.